Point links at git.coffeylabs.org after the move from GitHub

GitHub took the organization's repos and GHCR offline on 2026-09-20. Repo,
release, raw-file and clone links now go to Gitea at git.coffeylabs.org,
container images to registry.coffeylabs.org, and GitLab-style /-/blob paths
to Gitea's /src/branch form. Go module paths are identifiers and stay as
they are; links to GitHub issues and pull requests are left as history.

internal/docker/docker.go

@@ -66,7 +66,7 @@ func envValue(env, name string) string {
 }
 
 // RepoDigest is an image's by-digest reference in one repository, e.g.
-// ghcr.io/coffey-labs/ihasmail@sha256:..., which names exactly that image for
+// registry.coffeylabs.org/coffey-labs/ihasmail@sha256:..., which names exactly that image for
 // as long as the registry keeps it.
 func RepoDigest(ctx context.Context, image, repository string) (string, error) {
 	out, err := Output(ctx, "image", "inspect", "--format", "{{range .RepoDigests}}{{println .}}{{end}}", image)